Recovery of ammonia from distillation-gases.



W. MUELLER. RECOVERY OF AMMONIA FROM DISTILLATION GASES.

APPLICATION FILED SEPT. 3, 1910.

Patented; Nov. 26, 1912.

3 SHEETS-SHEET l.

W. MUELLER.

RECOVERY OF AMMONIA FROM DISTILLATION GASES.

APPLICATION IILED SEPT. 3, 1910, LQp fifigfl Patented Nov.26,1912.

3 SHEETS-SHEET 2.

nun uunuunuuunn W. MUELLER. RECOVERY OF AMMONIA FROM DISTILLATION GASES.

APPLICATION FILED SEPT,3,1910.

Patented Nov. 26, 1912.

a? @W/ flwwmawz circuit-by curving the ends of the chamber WILHELM MUELLER, OF ESSEN-ON-THE-RUHR, GERMANY.

RECOVERY OF AMMONIA FROM DISTILLATION-GASES.

roaasoo.

Specification of Letters Patent.

Patented i av. 26, 1912.

Application filed September 3, 1910. Serial No. 580,440.

T 0 all whom it may concern.

Be it known that I, WILHELM MUELLER, a citizen of Germany, residing at No. 1? Gutenbergstrasse, Essen-on-the-Ruhr, Germany, have invented certain new and useful Improvements in Recovery of Ammonia from Distillation-Gases; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification.

My present invention relates to improvements for the recovery of ammonium sulfate from hot distillation gases of coal or other fuel, and has for its object to simplify the apparatus required, to produce perfectly pure tar and sulfate of ammonia in a direct manner without the use of steam or lime and in a very efficient manner. 1

According to this invention-the distillation gases in their passage through the socalled ammonia saturator, which consists of an acid bath, cause the acid liquor therein to circulate so that particularly the surface liquor which acts on the incoming gases is constantly changed. Furthermore according to this invention the impurities which collect on the surface of the acid liquor forming the acid bath, are automatically removed in a continuous manner and thereby the surface of the bath presented to the incoming gases is always kept in a clean con dition so that the incoming gases always meet clean acid liquor;

In carrying out this invention between the point where the gases enter the acid bath chamber and the point wherethe gases leave said chamber, means are interposed in the path of said gases which force or cause the gases to repeatedly enter or dip into the liquor and thereby pass through a portionof the liquor at several different points in succession with the result that the gases set up or cause an active circulation of the liquor in the acid bath, one or more of the walls of the bath being so curved or formed that, a complete circulation is set up of the whole body (or practically the whole body) of the liquor of the bath. This circulation may either be caused to flow in a vertical in the vertical direction; or may be caused inner chamber It maybe arranged that any 'i like) is or are caused to pass over the top, edge of a wall or through an opening .or

openings provided for this purpose in the side or end Wall or both of the chamber and thus automatically remove such impurities from the surface of the acid bath or acid liquor.

The invention is illustrated in the accompanying drawings of which- Figure 1 is a diagrammatic view of a plant for treating distillation gases, the plant comprising the improved ammonia saturator. Fig. 2 shows the saturator in sectional elevation. Figs. 3 and 4 are transverse sections on lines X-X and ZZ respectively in Fig. 5. Fig. 5 is a pla'n of the apparatus shown in Fig. 2. Fig. 6 is a part section showing the battle plates pivotally mounted on to the flat top of the saturating chamber. Fig. 7 illustrates a modified construction of the saturator; Fig. 8 is a verti cal section and Fig. 9 a horizontal section through the saturator shown in Fig. 7.

Like reference letters indicate like parts throughout the drawings.

As may be seen from the drawings the apparatus (W) for removing the tar and cooling and washing the gas shown in Fig. 1 consists of. an. outer sheet-iron shell (3) inclosing an inner casing (4). Both the shell and the inner casing may be of round .or angular section. The outer chamber (A) serves for the preliminary cooling, while the B) is used as a washer which latter is filled with hurdles or grids. T he gas and washing-liquor are passed through the chamber (B) on the counter- 'current principle so as to obtain an intimate intermingling of the liquor with the ascending gases. 'Near the top of the apparatus there are provided vertical and horizontal screens through which the escaping gases have to pass. Spraying nozzles 6) arranged near the top serve for sprinkling the inner chamber. (B) as well as the outer chamber (A) with gas-water, oil or any other suitable washing-liquor. Near the bottom of the innerwashing chamber (B) there is provided a propeller or fan (8) driven from the outside by a bevel gear and motor ('7) or other suitableme'ans which fan serves to suck gases from the space (A) and force them upward. The gases are introduced into the apparatus, through one or two pipes. one of which (1) opens into the top part of the outer chamber (A), while another pipe delivers the gas into the middle of the inner chamber (Il) by means of an annular dist *ibution socket surtied gas leaves through exit-pipe (1st) Fig.

, 2 or re) after passing the last Unlike the common saturators. which are usually pro'ided with a bell-shaped cover, the present saturator has a flat or straight top (15) which lies between the inlet and the exit-pipes and is provided with a number of battle-plates (1(3) dipping into the bath and preferably inclined in the direction of the movement of the gases. hese plates may be corrugated. and may be provided with serrated edges. To enable the immersion of the plates to be regulated as desired, the plates may be pivot-ally mounted on the cover as shown in hi (3 and may be connected by an operating rod (17) or similar means. Atthe end of the saturator chamber there is a froth-chamber (19). The partition wall (18) has concave guidesurface (18) for deflecting the stream of liquid downward. Screens (19) are ar ranged in the chamber (19) and strain the liquor as the latter returns to the bath. The tar-froth and other impurities which accumulate in the froth-chamber (19) run off by a pipe (20) into a collecting tanlt (20 see Fig. 1. In the middle zone of the saturator are placed several. perforated battle plates (21) for retaining the salts which might otherwise be carried round by the circulation produced in the bath.

In the modification in Figs. 7 to St the gas battle-plate (16), is not discharged directly outward. but is led through lateral. flues or channels (22) which are connected by transverse pas. ages ('23), so that the gases before leaving the apparatus have to remain for some time in these spaces at the sides and in the roof of the saturating chamber proper and up part of their heat to the honor of the bath. For

this construction of saturator the wall (18) of the froth chamber (19) is formed with two concave guide surfaces (18) for deflecting the liquor laterally. Similar guide surdegree of 1 faces (21) are formed at the opposite end of the saturator. I 1th this arrangement the froth is skimmed otf. and the flow ot' the liquor at and near the surface is diverted- 'connnunicates at the bottom with a 'verti al shaft (25) from which the crystalline salts of ammonia are removed by means of a. common steam ejector (26).

The saturators according to Fig. 2 or Fig. 7 are filled with a solution of sulfuric acid of about 30 to degrees Baum with a few percentages of free acid. the level of the liquid being preferably about two inches from the top of the chamber, this level being maintained constant by a supply of fresh acid from a high-le el-tank' ('27) Fig. 1 through a pipe (1 .8) provided with a suitable regulating cock. In addition to the pipe (28) another pipe (2 is arranged in the inlet pipe (12) and provided with a sprinkling nozzle (30) through which fresh acid is sprayed and mixed directly with the gas stream in order to facilitate ant accelerate the absorption of the ammonia in the saturator. In order to increase the heat of reaction in the apparatus. the supply of fresh sulfuric acid may be preliminarily heated by a steam-coil or other suitable means in the reservoir (27) so that the acid enters the saturator ,in a very hot state. For further improvement of the temperature of the bath the side walls of the saturating chamber can also be provided with a steam pipe coil (5p).

All inner surfaces of the saturator which come into contact with acid are lined with l lead. The gas inlet or exit-pipe (12, 11 5 1 141 of the saturator may be connected with a blowing machine or, exhauster (36), Fig. 1. of us construction which forces or draws the gases to be washed through the apparatus and forces them for example into a gasometer. The apparatus is preferably placed in the immediate neighborhood of the ovens or retorts producing the and the pipes 1 9 10 and 11 are jacketed in order to avoid unnecessary cooling of the gas.

The process of treating the gases in the apparatus above described is as follows: In order to'remo e the by-products, more espccially the tar and the ammonia, from coke-oven or distillation gases of coal or other fuel in a direct manner. it is essential first to separate the tar and other impurities from the hot gases, so that: the ammoniacalsalts may not be polluted by tarry substances and rendered unsalable. To attain this the hot gases which come direct from the ovens or retorts (O) and are somewhatv that the gases leave the apparatus at a cooled in the collecting mains (V) and the pipes, are introduced at a temperature of about 200 degrees centigrade into the apparatus (W) see Fig. 1. The gases pass through the pipe (1) and enter the upper and the outer chamber and descend to the openings (9) through which theypass to thefan (8) which forces them up into the washer. During their passage through the outer chamber the gases cool down to a temperature of about 100 degrees C, the major part of the tar, dust and other impurities being condensed and separated from the gases. To prevent the formation of tar or dust deposits on the sides the latter may be sprinkled with gas liquor or water from the top by means of the spray nozzles (6). The gases now pass upward through the washer (B) containing hurdles or grids.

On passing through these hurdles the gas is repeatedly split up into numerous fine streams and is uniformly distributed throughout the whole space of the washer. Owing to the increased velocity imparted to the gases by the propeller or fan (8) and the fact that the gases dash or strike many times against the horizontal surfaces of the grids or hurdles all solid and liquid substances are separated. Since the hurdles are continuously sprayed from above and all surfaces are moistened by the liquor, the gases. in addition to the separating action due to the repeated impact, are brought into intimate contact with the washing-liquor and are therefore purified. The purified. gas passes through the screens (5) arranged in the top part of the washer. which screens retain even'the slighest traces of mist and tar-fog and escapes in a dry. hot state through the pipe (10) leading direct to the saturator (S).

The products of condensation obtained by the cooling and washing of the gases. viz. dust. tar, oil and gas-water collect in the bottom part of the apparatus (W) from which they automatically run through a siphon pipe (9) to a settling tank wherein separation according to specific gravity takes place. The recovered gas-water and.

if retmircd. al o the light thin tar may'advantageously be pumped to thetop of the apparatus and used again as washing-liquid. in which case they may be introduced through the spraying nozzles (6). The excess of gas-water whicl cannot be used for washing and contains only solid combinations of ammonia. is supplied without any further treatment to the acid bath of the saturator, or is otherwise disposed of as desired.

The hot gases passing through the outer chamber (A) keep the inner chamber ot the washer at a constant high temperature which may be regulated in such a manner temperature of about -80 degrees C. at which temperature all the ammonia still remains volatile. For this reason, the previously condensed hot gas-water or hot thin tar should be employed for spraying the I hurdles so as to effect the washing of the gases without condensing the ammonia con- "stituents.

When distilling coal or other fuel which produces gases very rich in tar, 1t is preferred to collect the gases 1n two fractions corresponding "to about the first threefourths and the last quarter of the period of distillation, separate mains being used for the two fractions. The gas obtained during the first three-fourths of the distillation. which gas contains most of the tar and the impurities, is introduced through pipe (1) and has to pass through the whole of the apparatus in the manner already described. The gas produced during the last quarter of the distillation is introduced. through pipe (2) and duct (2) in the middle of the apparatus where it mixes with the gases produced during the first threefourths of the distillation process. and is subjected herewith to the washing action. As is .well known the gases of the last period are much hotter than the gases rich in tar produced during the first period. and often cause incrassation ot' the tar in the apparatus, if the gases of both periods are treated simultaneously. This drawback is however obviated if the gases enter the apparatus separately and are mixed only after the gases of the first period are, more than half washed. By introducing the hot gases of the second period only into the upper portion of the washer, the hot gas-water (or thin tar) used as washing liquor is still further heated whereby the ammonia constituents contained in the gas-water is vaporized and caused to escape together with the gas.

The hot gas still charged with all the ammonia combinations is passed from the washer (W) through pipes, (10) and (11) directly into the sulfuric acid bath of the saturator (S), see Fig. 2 or Fig. 7. It enters the bath through the widened end of pipe (12) with its distributionjh oods (12 or through a number of smaller pipes (13). bubbles up through the bath to the top (15) of the saturator, and then moves in a thin and wide stream over the surface of the bath to the exit. being compelled to pass repeatedly into the acid by the bathe-plates (16) which dip into the bath and are inclined in the direction of the gas current. All the impurities collecting on the surface. such as tar-froth or the like. are carried toward the end of the bath and caused to pass over the wall (18) into the froth-chamber (19) from which they run outward'into a forward by the circulation of the bath and tank or cask (2%) through a pipe (20). The liquor carried together with the froth into the chamber (19) returns to the bath through the screensv (19) at the bottom. In this way the surface of the bath is always kept in a clean condition. The concave inner guide surface (18 Fig. 2 or (18") and (2%) Figs. 7 and'9 of the wall (18) of the chamber (19) directs the flow of the liquid back, either in the downward direction as in Fig. 2, or in the lateral directions as in Figs. 7 and 9. Owing to this circulation the up per zone of the acid bath is thoroughly stirred and the efiiciencv is increased while the consumption of the acid is reduced to a minimum. For the same purpose and in order to prevent condensation of the aqueous vapors contained in the gas. the saturating chamber is heated laterally by means of the steam pipe coil (87)) and the additional sulfuric acichor acidlye is supplied to the saturator at a high temperature through pipe (28 or 29) whereby the reaction heat is increased. By the introduction of hot sulfuric acid from the reservoir (27) through pipe (29) and nozzle (30) direct into the gas inlet pipe (12) of the saturator a more intimate intermingling with the gas and a quicker absorption of the ammonia is attained.

The plates (21) arranged according to Fig. 2 in the middle zone of the saturator retain the solid salts of ammonia carried cause the salts-to settle. These perforated plates (21) are arranged in the construction according to Figs. 7, 8 and 9 near the entrance of and also further along the lateral passages (22). The solid salt of ammonia produced in the saturator by the reaction of the ammonia upon the sulfuric acid drops into the lower collecting chamber (25), and is lifted in a well known manner by means of a steam ejector (26) to a draining table (31) from which latter it is delivered to the centrifugal drying machine (32) which leaves the salt in a salable condition and ready to be stored. The separated liquor runs intoaliquor-pot (33) which automatically returns the liquor to the bath in the saturator for further treatment. The gases which are entirely purified from tar and ammonia are finally drawn from the saturato-r through an acid separator (3 T) and pipe (35) by means of an exhauster or blowing engine (36) which forces them into a gasometer in which they are stored to be used for illuminating, heating or motivepower purposes.

The new method of producing the ammonia in a direct manner without the aid of steam or lime and the simplified construction of the apparatus enable the recovery of the by-products to be effected in a much more economical way than hitherto, and

tacle adapted to contain have the-further advantage that the employment of the usual arrangement for washing and distilling with their inevitable poisonous efiiuent liquor and mud nuisance is entirely dispensed with.

The present invention renders it possible not only to obtain a complete absorption of all the ammonia from the gas without any employment of the usual so-called after-separator, but also a clean white salt of arm inonia is obtained, while the consumption of acid is reduced to practically the minimum.

I-claim:

1. A saturator for the treatment of distillation gases comprising a closed receptacle adapted to contain an acid bath, a gas inlet thereto and exit therefrom, and gas defleeting means disposed between said inlet and exitand adapted to depend into said bath and obstruct the path of the gases through the space above the surface of said bath, said gases being thereby caused to descend several times beneath the surface of the bath in performing their course from the inlet to the exit substantially as set forth.

2. A saturator for the treatment of distillation gases comprising a closed receptacle adapted to contain an acid bath, a gas inlet thereto and exit therefrom, gas deflecting means disposedbetween said inlet and exit and adapted to depend into said bath and obstruct the path of the gases through th space above the surface of the said bath said gases being thereby caused to descend several times beneath the surface of the bath in performing their course from the inlet to the exit, and an overflow wall arranged adjacent to said exit and havingits upper edge at about the level of the surface of said bath substantially as set forth.

3. A saturator for the treatment of dis tillation gases comprising a closed receptacle adapted to contain an acid bath, a gas inlet depending into said bath at one end thereof distributing means on said inlet, gas deflectors depending from the cover of said receptacle, :1 gas exit from the opposite end of said bath, and a combined overflow wall and liquid deflector at the exit end higher level than the lower edges of said tially as set forth.

i. A saturator for the treatment of dis tillation gases comprising a closed recepan acid bath, a gas inlet depending into said bath, at one end thereof, distributing devices in connection with said inlet, gas deflectors depending from the cover of said receptacle. a gas exit from the opposite end of said bath, a curved concave surface at one end of said bath adapted to deflect the current of liquid set up by the flow of gas, and an overflowwall of said receptacle the upper edge of said wall befor said liquid at the exit end of said bath bounded on one side by a wall formed with the oi'ertloy'y edge being at a higher level than the lower edges of the depending deflectors substantially as set forth.

Apparatus for recovering ammonium sulfate from distillation gases comprising. in combination, a saturatingchamber adapted to be filled almost; to the top with a solution of sulfuric acid and provided with a horizontal top; transverse bathe-plates (lipping into the liquor 01 the bath and adapted to be angularly adjusted by means of a guide rod; lateral fines or channels around the saturating chamber proper. said tines being connected at the top by transverse fines; a steam pipe coil in the side walls of the saturating chamber: a fl'tllli-(illilllllKl concave guide-surfaces facing toward the bath for diverting the flow of liquor in the bath: concave guide-surfaces arranged at the opposite end of the chamber, a gasinlet pipe provided with distrilaition means, an acid supply pipe entering said gas inlet pipe. a spray nozzle on the delivery end of said supply pipe, and a exit pipe arranged on the saturating chamber.

In testimony that I claim the foregoing the my invention. 1 have signed my name in presence of two subscribing witnesses.

NILHELM MUELLER. [Ls] itnesses:

CHAS. J. Vvinoii'r. ALFRED HRNKRL. 

